Arc-lamp.



J. T. H. DEMPSTER.

ARC LAMP.

APPLICATION FILED MAY 17,1912.

1,132,307, Patented Mar. 16, 1915.

Witnesses: Inventor:

John T. H.Dempster,

Hus fittorney.

UNITED STATES PATENT OFFICE. I

JOHN '1. H. DEMPSTER, OF SCQHENEOTADY, NEW YORK, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK. I

ARC-LAMP.

Specification of Letters Patent.

Patented Mar. 16, 1915.

To all whom it may concern Be it known that I, JoHN T. H. DEMP- STER, acitizen of the United States, residing at Schenectady, county ofSchenectady, State of New York, have invented new and usefulImprovements in Arc-Lamps, of

which the following is a specification.

My invention has reference to an arc lampof the flaming-type.

It has heretofore been proposed to make electrodes which will support aflaming are by mixing a salt or salts, the vapors from which are adaptedto impart luminosity to the arc, with carbon, and make electrodes fromsuch mixture. With electrodes of this trodes at such a point that thematerial is fused by the heat from the arc and is vaporized into thearc.

My invention is illustrated in the accompanying drawings, in whichFigure 1 is a vertical sectional view, partly in elevation, showing alamp in which my invention is embodied, and Fig. 2 is a side elevationshowing the arrangement of the electrodes.

I have shown my invention embodied in an arc lamp of the inclosed type,although it will be understood that it is not limited to this characterof lamp.

. In the drawings, 1 is the bottom plate of the lamp' secured to andsupported by suitable spacing bars 2. The lamp which I have showncomprises a rather large fiat condensing chamber 3 in which the fumesfrom the are are deposited. This chamber is formedby'an upper member 4;l and a lower member 5 suitably joinedatogether. The upper member 4 isprovided at its inner edge with a vertical cylindrical extension 6,having at its upper edge an inwardly extending flange 7 which is securedto the bottom plate 1 of the lamp. The lower portion 5 of the condensingchamber extends somewhat downwardly and inwardly and its inner edge isturned down to form a vertical wall 8, within which is received andsecured an annular ring 9. The inner globe 10 is seated against the ring9 and is held in engagement with the same by a spring seat 11 of anyusualconstruction, the bails for which are not shown in the drawing. Theouter globe 12 is supported at the top by an. annular ring13 which mayconveniently be hinged at 14 and secured in position by a suitablefastening means 15, the details of which are not here shown. The upperelectrode 16 comprises two converging members 16 and 16 which arereceived within sleeves 17 and 18 within which the members 16 and 16 areadapted to slide freely. A lower electrode 19 cooperates with the upperelectrode and it will be understood that suitable mechanism is providedin the lamp for separating the lower .electrode from the upper toestablish the arc, and if desired, for regulating the same. The rod orbar 20 is formed of some fusible material, the vapors from which areadapted to impart luminosity to the arc, and is so arranged that it isfed into abutting engagement with the. upper electrode at such a pointthat the heat from the arc will fuse the tip of the bar 20. The bar 20is guided by a sleeve 21, and I have here shown the same fed intoabutting engagement with the upper electrode by gravity. It will beunderstood, however, that additional means may be provided forpositively feeding this bar if desired. A casing 22 for p the lampsurrounding the cylindrical extension 6 and supported by.-the upperpor-- tion 4 of the depositing chamber, houses the operating mechanismof the lamp. The casing may conveniently be formed in two portions whichare fastened together at 23.

In operation the electrodes are separated to establish the arc. As soonas the tip of the. upper electrode becomes sufiiciently heated from thearc, the tip of the bar 20 which is in engagement with the upperelectrode begins to fuse, and thematerial therefrom runs down over thearcing face of the upper electrode where the material, of which the bar20 is composed, is vaporized and carried into the arc impartingluminosity to the same. Such an arrangement possesses the advantage thatthe amount of light giving materialentering the arc-is automaticallyregulated. If, for instance, the tips of the electrodes become heated toan abnormal temperature, more .of the fusible material will be meltedand running over the tip of the upper electrode will cool the same,thereby decreasingthe amount of material that will be fused. On theother hand, if the tip of the upper electrode is cooled to an abnormaltemperature, less of the fusible material will be melted, therebypermitting the temperature of the tip of the positive electrode toincrease.

It will be seen that my invention permits the use of electrodes forsupporting the are which are made of good conducting material, such ascarbon, Without burdening the electrode with light giving materialswhich. are usually poor conductors and which interfere, whenincorporated in the electrode itself, with the proper burning of thearc. lVhen' made of carbon the electrode may be made more dense thanwould be possible if the same were .miXed with light giving materials,thereby increasing the life of the electrode. At the same time the laborinvolved in thoroughly. mixing the light giving material with the carbonis avoided.

While I have mentioned carbon as a material well adapted for theelectrode material in my invention, it will be understood that in case astill more slowly consuming material is desired, then metallicsubstances may be employed for supporting the are. In such case themetallic, substances of the electrodes themselves give luminosity to thearc, which luminosity may be enhanced and the color of the light may bemodified by theuse of my invention.

A bar or rod may be made, in accordance with my invention, by meltingtogether equal parts of calcium fluorid', sodium fluorid and potassiumfluorid, and casting the molten mixture into the form of a rod or bar,as desired. In case it is desired to further lower the melting point ofthe rod, the proportion of the alkaline materials may be increased.While I have mentioned fiuorids as well suited for the purpose of myinvention, it will be understood that it is not limited to any specificlight giving materials, as other materials such as titanatesand oxids,or mixtures with or without the material would be made to abut againstthe electrode at a point farther removed from the arc than would a rodof more refractory material. What I claim as new and desire to secure byLetters Patent of the United States, is 1. In an arc lamp, a-pair ofcooperating electrodes between which an arc may be formed, incombination with a fusible rod containing or composed of light givingmaterials, abutting against one of the electrodes in such vicinity ofthe are as to feed the fusing rod-material into the arc.

2. In an arc lamp, the combination of an upper and lower electrodebetween which an arc may be formed, and means for imparting luminosityto the arc, consisting of a fusible rod containing or composed of lightgiving materials and adapted to be held in abutting engagement with theupper electrode above the arc.

3. In an arc lamp, a pair of electrodes betweenv which an arc may beformed and supported, one of said electrodes having arcing facemaintained substantially stationary with reference to the lamp, incombination with a rod of fusible light giving material held in abuttingengagement with said electrode in such vicinity of the arc asto feed therod-material into the are.

4. In an arc lamp, an upper and a lower electrode, between which an arcmay be formed and supported, the upper electrode comprising a pair ofabutting members, and

a bar of fusible light giving material held in abutting engagement withsaid abutting members in the vicinity of the arc.

In witness whereof, I have hereunto, set

my hand this 16th day of May, 1912.

JOHN T. H. DEMPSTER.

Witnesses:

BENJAMIN B. HULL, HELEN ORFORD.

